Add notification that LTS Interface instructions are specifically for Cheaha

[wwarriner]

What is inaccurate?

The page at https://docs.rc.uab.edu/data_management/lts/interfaces/ assumes the user is using Cheaha, but does not mention this assumption. It is also not under the Cheaha Guide section.

This has created confusion about the commands failing completely when used on personal machines from users who are unfamiliar with Cheaha, but want to use LTS. This came up because a user wanted to backup a portable hard drive to their personal LTS, but hadn't used Cheaha before and little experience with command line interfaces and programs.

What I'd like to see:

1. A notice at the top of the page mentioning the existing instructions assume the user is using Cheaha (we can link to the HPC Desktop and OOD pages for now)
2. Instructions on how to install s3cmd (or where to find the instructions) for use on a personal machine.

Where is the inaccuracy?

https://docs.rc.uab.edu/data_management/lts/interfaces/